Development and Reliability of a Visual-Cognitive Reactive Triple Hop Test

CONTEXT

Current lower-extremity return to sport testing primarily considers the physical status of an athlete; however, sport participation requires continuous cognitive dual-task engagement. Therefore, the purpose was to develop and evaluate the reliability of a visual-cognitive reactive (VCR) triple hop test that simulates the typical sport demand of combined online visual-cognitive processing and neuromuscular control to improve return to sport testing after lower-extremity injury.

DESIGN

Test-retest reliability.

METHODS

Twenty-one healthy college students (11 females, 23.5 [3.7] y, 1.73 [0.12] m, 73.0 [16.8] kg, Tegner Activity Scale 5.5 [1.1] points) participated. Participants performed a single-leg triple hop with and without a VCR dual task. The VCR task incorporated the FitLight system to challenge peripheral response inhibition and central working memory. Maximum hop distance, reaction time, cognitive errors, and physical errors were measured. Two identical testing visits were separated by 12 to 17 days (14 [1] d).

RESULTS

Traditional triple hop (intraclass correlation coefficients: ICC(3,1) = .96 [.91-.99]; standard error of the measurement = 16.99 cm) and the VCR triple hop (intraclass correlation coefficients(3,1) = .92 [.82-.97]; standard error of the measurement = 24.10 cm) both demonstrated excellent reliability for the maximum hop distance, and moderate reliability for the VCR triple hop reaction time (intraclass correlation coefficients(3,1) = .62 [.09-.84]; standard error of the measurement = 0.09 s). On average, the VCR triple hop resulted in a hop distance deficit of 8.17% (36.4 [5.1] cm; P < .05, d = 0.55) relative to the traditional triple hop.

CONCLUSIONS

Hop distance on the VCR triple hop had excellent test-retest reliability and induced a significant physical performance deficit when compared with the traditional triple hop assessment. The VCR triple hop reaction time also demonstrated moderate reliability.

Advanced training enhances readiness to return to sport after anterior cruciate ligament reconstruction

Patients with anterior cruciate ligament reconstruction (ACLR) are often psychologically and physically under-prepared for sports participation. This study compared readiness to return to sport based on completion of advanced training after ACLR. Patients with ACLR who self-selected participation in a 6-week group-format advanced training program (TRAINING) were compared to age- and sex-matched patients who did not participate (NoTRAINING). Each group had 23 participants (14 females). Advanced training consisted of plyometric, strengthening, and agility exercises. Baseline and follow-up testing included psychological measures (Anterior Cruciate Ligament Return to Sport after Injury [ACL-RSI]; Tampa Scale for Kinesiophobia [TSK-11]; Knee Activity Self-Efficacy [KASE]; and fear intensity for the primary fear-evoking task or situation) and a hop test battery. Return to sport criteria were ACL-RSI score ≥70 points and limb symmetry index ≥90% on all hop tests. At follow-up, KASE score was higher in TRAINING than NoTRAINING (92.7 vs. 89.1 points; respectively), but ACL-RSI, TSK-11 and fear intensity scores were not significantly different between groups. Return to sport criteria passing rate was not significantly different between groups at baseline (TRAINING: 13%, NoTRAINING: 30%) or follow-up (TRAINING: 52%, NoTRAINING: 43%); however, the distribution of criteria met at follow-up differed with more patients in TRAINING than NoTRAINING meeting hop test criteria (30% vs. 4%, respectively) and more patients in NoTRAINING than TRAINING failing to meet any criteria (25% vs. 0%, respectively). Advanced training after ACLR facilitated readiness for sport participation by improving confidence and hop performance, but may not have a preferential effect on fear.

Establishing Age- and Sex-Specific Norms for Pediatric Return-to-Sports Physical Performance Testing

Background:

Graft tears and contralateral anterior cruciate ligament (ACL) tears are common in pediatric athletes after ACL reconstruction. Use of objective return-to-sports (RTS) criteria, in particular physical performance tests (PPTs), is believed to reduce the incidence of secondary injury; however, pediatric norms for these tests are unknown.

Purpose:

To establish a proof of concept for the creation of age- and sex-based norms for commonly used RTS PPTs in healthy pediatric athletes, allowing the creation of growth curves for clinical referencing.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

A total of 100 healthy people who were between the ages of 6 and 18 years and involved in organized sports were enrolled, with even distributions of age and sex. All participants underwent 9 common RTS PPTs: stork test, stork test on Bosu, single-leg squat, single-leg squat on Bosu, clockwise and counterclockwise quadrant hops, single-leg hop for distance, 6-m timed hop, and triple crossover hop for distance. Mean performance across limbs was calculated for each individual. Chronological age, height, weight, sex, and self-reported Pubertal Maturational Observational Scale (PMOS) score were recorded. Univariable and multivariable models were created for each PPT, assessing the importance of the recorded descriptive variables. Quantile regression was used to create growth curves for each PPT.

Results:

The cohort was 52% female, and the mean ± standard deviation age was 11.7 ± 3.6 years. PMOS was highly correlated with age (r = 0.86) and was excluded from the regressions. In univariable regression, age, height, and weight were strong predictors of performance for all PPTs, whereas sex was a predictor of performance on the single-leg and triple crossover hops for distance (with males outperforming females). Height and weight were excluded from multivariable regression because of multicollinearity with age. Multivariable regression showed predictive patterns for age and sex that were identical to those shown in the univariable analysis. Given ceiling effects, quantile regression for the stork tests was not possible, but quantile regression growth curves were successfully created for the 7 remaining PPTs.

Conclusion:

Chronological age and sex accurately predicted performance on common RTS PPTs in pediatric patients. The growth curves presented herein could assist clinicians with benchmarking pediatric patients postoperatively against a healthy athletic cohort.

ACL Return to Sport Testing: It's Time to Step up Our Game

Patients and physicians have long looked to physical therapists to help determine an athlete's readiness to return to sport (RTS) following anterior cruciate ligament reconstruction (ACLR). This is a complex decision that must take into account biological healing, joint stability, functional performance, and psychological readiness. Considering that the vast majority of medical professionals use time as the sole determinant of an athlete's readiness, and few are using performance-based criteria, it appears as though our profession is failing to capture the necessary information to make this weighty recommendation. The time is now to take a hard look at current practice patterns with RTS testing and push the envelope forward. The purpose of this clinical commentary is challenge our failing status quo by disseminating a robust model for RTS testing that incorporates temporal and criterion-based factors, as well as intrinsic and extrinsic data.

LEVEL OF EVIDENCE

5.

The Role of Fatigue in Return to Sport Testing Following Anterior Cruciate Ligament Reconstruction

BACKGROUND

Fatigue may play a role in anterior cruciate ligament (ACL) injury, but has not been incorporated into objective test batteries for return to sport decisions following ACL reconstruction (ACLR) surgery. The effect of fatigue on muscle function and performance following surgery and rehabilitation has been poorly studied.

PURPOSE/HYPOTHESIS

The purpose of this study was to assess the effect of fatigue on performance of various hop tests used in clinical rehabilitation settings by examining LSI scores. The authors hypothesized that participants will have worse limb symmetry index scores following the fatigue protocol and that the operative limb (ACLR) will have a greater decline in function than the non-operative limb (CON).

STUDY DESIGN

Cross-Sectional Study.

METHODS

Participants (n=21 [Male = 15, Female = 6]; AGE = 24.6 ± 9.3) were at least six months post ACLR and in rehabilitation. Testing was performed over two separate sessions in either a non-fatigued (NFS) or fatigued state (FS). In the FS, individuals performed a series of exercises to exhaust muscular endurance, strength, and power systems, after which they performed as battery of seven hop tests (single hop for distance, triple hop for distance, crossover hop for distance, 6-meter timed hop, lateral rotation hop for distance, medial rotation hop for distance, and vertical jump for height). A 2(limb) x 2(time) ANOVA was used to compare limbs between each state.

RESULTS

Differences between limbs (CON vs ACLR) were observed for all hop tests in the NFS whereby the ACLR limb was observed to have reduced performance (↓5.4-9.1%, p <0.05). When tested in the FS, significant differences in performance between limbs remained for only the crossover (↓4.9%), medial rotation (↓7.1%), lateral rotation (↓5.5%), and vertical hop (↓10.0%)(p<0.05). When comparing the NFS and FS states, only the CON limb was observed to have significant decreases in performance of the Triple Hop (↓7.4%), Crossover (↓8.7%), and Lateral Rotation (↓5.2%)(p<0.05).

CONCLUSIONS

Following ACL reconstruction, there appears to be a greater loss in jump performance in the CON limb in the FS. These findings suggest it may be crucial to consider and assess the endurance of both limbs rather than just the ACLR limb when determining readiness for return to play.

LEVEL OF EVIDENCE

Level 3.

Combining Inertial Sensors and Machine Learning to Predict vGRF and Knee Biomechanics during a Double Limb Jump Landing Task

(1) Background: Biomechanics during landing tasks, such as the kinematics and kinetics of the knee, are altered following anterior cruciate ligament (ACL) injury and reconstruction. These variables are recommended to assess prior to clearance for return to sport, but clinicians lack access to the current gold-standard laboratory-based assessment. Inertial sensors serve as a potential solution to provide a clinically feasible means to assess biomechanics and augment the return to sport testing. The purposes of this study were to (a) develop multi-sensor machine learning algorithms for predicting biomechanics and (b) quantify the accuracy of each algorithm. (2) Methods: 26 healthy young adults completed 8 trials of a double limb jump landing task. Peak vertical ground reaction force, peak knee flexion angle, peak knee extension moment, and peak sagittal knee power absorption were assessed using 3D motion capture and force plates. Shank- and thigh- mounted inertial sensors were used to collect data concurrently. Inertial data were submitted as inputs to single- and multiple- feature linear regressions to predict biomechanical variables in each limb. (3) Results: Multiple-feature models, particularly when an accelerometer and gyroscope were used together, were valid predictors of biomechanics (R² = 0.68–0.94, normalized root mean square error = 4.6–10.2%). Single-feature models had decreased performance (R² = 0.16–0.60, normalized root mean square error = 10.0–16.2%). (4) Conclusions: The combination of inertial sensors and machine learning provides a valid prediction of biomechanics during a double limb landing task. This is a feasible solution to assess biomechanics for both clinical and real-world settings outside the traditional biomechanics laboratory.

CRITERION-BASED REHABILITATION PROGRAM WITH RETURN TO SPORT TESTING FOLLOWING ACL RECONSTRUCTION: A CASE SERIES

Background

Less than 50% of those sustaining an anterior cruciate ligament (ACL) injury return to their preinjury level of sports participation or participate in competitive sport at two to seven years post ACL reconstruction (ACLR). After ACLR, it has been reported that frequency of subsequent ACL tears has reached as high as 31%.

Purpose

The purpose of this case series was to evaluate return to sport and reinjury rates following the use of a criterion-based rehabilitation protocol with a final return to sport test that utilizes minimal equipment following ACL reconstruction.

Study Design

Case series.

Methods

Following ACL reconstruction, participants were included if they had a goal of returning to their pre-injury sport or level of activity, were between 16 and 50 years of age at the time of evaluation, had at least 25 physical therapy visits covered by insurance, and planned to complete physical therapy until clearance for return to sport.

Results

Forty-three participants met the inclusion criteria and enrolled in the study. Twenty-one participants completed the full course of rehabilitation including passing their return to sport test and nineteen participants completed the two-year follow-up. Data obtained at two years indicated that 84% were able to return to their preinjury level of sports competition. A smaller percentage (16%) were able to return to a reduced level of sport and only one participant reported a second ACL injury.

Conclusion

Participants that completed the full course of rehabilitation and passed return to sport testing had a larger percentage that were able to return to preinjury participation levels than currently reported in the literature. This case series did not exclude participants based on graft type, single vs double bundle procedure, ACL revision surgeries, nor concomitant procedures or injuries.

Level of Evidence

Level 4.